Clinical recognition of pulmonary embolism (PE) in patients with congestive heart failure (CHF) is relatively common but notoriously difficult. Plan is to measure fibrin split products (FSP) three times a week in a series of patients with CHF in an attempt to recognize PE early. If FSP's appear, further diagnostic tests will be performed (scans, angios) and appropriate therapeutic measures instituted. Another attempt will be made to produce left ventricular failure (LVF) by PE in dogs. Chronic RVF will be produced by producing tricuspid insufficiency and pulmonary arterial banding. Pulmonary embolism will then be produced and LV hemodynamics recorded (pressures, output, dP/dt, dPdt/p (both total and developed), chamber volumes, ejection fraction). It may be necessary to reduce LV function before PE by embolizing the left coronary artery. If LV dysfunction is produced by these measures, attempts will be made (1) to explain the genesis of the LVF and (2) to explore methods for its correction.